Erectile dysfunction (ED) and urinary incontinence after bilateral nerve-sparing radical prostatectomy (BNSRP) still remain major causes of morbidity. Phosphodiesterase type 5 inhibitors (PDE5-Is) have a role in the treatment of ED after BNSRP. Several studies in patients with ED and lower urinary tract symptoms demonstrated that PDE5-Is could improve both erectile function and urinary symptoms. The aim of this study was to compare the efficacies of two dosing regimens of 20 mg tadalafil (on-demand and 3 times per week) and to assess the role of tadalafil in recovery of erectile function and continence after BNSRP. We conducted a single-center, prospective, randomized controlled trial of three times per week versus on-demand tadalafil 20 mg and a control group after BNSRP. A total of 129 preoperatively potent and continent patients were included in the study. The patients were evaluated at 6 weeks and 12 months postoperatively for erectile function and continence status. There was no significant difference between all three groups with respect to erectile function at 6 weeks after the surgery. Twelve months after the surgery, the International Index of Erectile Function score was significantly higher in the group using tadalafil 20 mg three times per week. However, there was no significant difference between the treated groups and the control group with respect to the continence status at 12 months after the surgery. There was no correlation between incontinence and ED after the surgery in all groups. Tadalafil 20 mg three times per week is an efficacious and well-tolerated treatment option for ED after BNSRP. Treatment with 20 mg tadalafil either three times per week or on demand cannot improve continence recovery after BNSRP compared with the control group. Copyright (C) 2014, Kaohsiung Medical University. Published by Elsevier Taiwan LLC. All rights reserved.